Brian Carroll, head of development at rural social housing provider Hastoe Group, talks about the cost and design of its Passivhaus drive
How many houses do you build a year and what proportion are to Passivhaus standard?
We build about 200 new homes a year, of which we aim to build about 40 to Passivhaus standards. At the moment, building to Passivhaus standard costs between 10 to 15 per cent more than our default standard – Code for Sustainable Homes level 4 (CSH). We expect this premium to reduce over time as the industry becomes accustomed and as we find the most effective way of achieving it.
Why is Hastoe commissioning so many Passivhaus homes?
To reduce the fuel poverty of our residents. Hastoe works mainly in rural areas, which don’t have mains gas. With the Passivhaus standard homes, our residents benefit from fuel bills that are about 10 per cent of the average UK fuel bill.
Will you stick with the Wimbish development as a template or are new designs an option for future schemes?
We work in rural areas across the whole of southern England. Many sites are very sensitive from a planning perspective. In order to produce Passivhaus schemes across this wide area, we need to design houses that fit with their surroundings. Our second Passivhaus scheme in Ditchingham, Norfolk, looks very different from Wimbish, as it is situated next to listed buildings.
How important do you think architecture is to your tenants?
Most people appreciate living in well-designed buildings within an attractive environment. Our residents are no different. Resident surveys show a consistently good satisfaction rating.
Are BREEAM/Code for Sustainable Homes not enough?
We generally build to CSH level 4. While this increases overall sustainability, it does not achieve the high levels of fuel efficiency that Hastoe strive for. We see the Passivhaus and CSH level 4 standards as complimentary, so when we build to Passivhaus standards we also require the scheme to achieve CSH level 4.
Your Passivhaus schemes are on large sites; would you consider using it on denser, urban sites?
We work mainly in rural areas and therefore our sites tend to be less dense than those in towns and cities. However, the size of the scheme is not the driver for us, as we build a range of sizes, typically from about four up to 25 homes.
Do you struggle to find appropriate architects?
When we developed our first Passivhaus scheme, there was a lack of knowledge in the sector. However, Chris Parsons of Parsons + Whittley embraced the concept and undertook the training. We now work with many different architects as Passivhaus becomes more widely known about and practised.